Various applications are known wherein a special clip is used to flush mount a plate within a corresponding opening in an extrusion. One such example is found in U.S. Pat. No. 3,479,851, wherein clips are used to flush mount a lock frame structure to an extruded door stile. The extruded door stile has an opening configured to receive the lock frame structure therewithin. The door stile extrusion has a longitudinal channel formed thereon which is intersected by the lock frame opening. Thus, portions of the channel lie adjacent opposite ends of the lock frame opening. The mounting clips each have a tongue portion and a head portion, the tongue portion being configured to be received within the channel of the extrusion, and the head portion extending into the lock frame opening and having a bore formed therein. The bores are positioned such that when the clips are installed on the door stile extrusion and the lock frame is positioned within the opening, corresponding bores in the lock frame align with the bores in the clips. Threaded fasteners are then used to secure the lock frame to the clips, thereby to mount the lock frame to the door stile extrusion.
While the clip arrangement disclosed in the aforementioned U.S. Pat. No. 3,479,851 provides generally satisfactory results when only a single clip is used at either end of the mounted object, somewhat different problems arise when such clips are used to mount a wider flush plate within an opening in an extrusion. An example of such an arrangement is shown in FIG. 1, wherein a prior art mounting tray is mounted within a corresponding opening in a transom bar to conceal a door opener. In this arrangement, the transom bar extrusion has parallel, spaced-apart channels formed therewithin, and a clip generally of the type disclosed in the aforementioned U.S. Pat. No. 3,479,851 is installed into each channel. Bores in the heads of the clips are supposed to align with corresponding spaced-apart bores in the mounting tray to receive threaded fasteners.
However, prior art clips of the type described suffer certain disadvantages. The clips can easily be under-or overdriven into their respective channels during installation such that the bore in the head of the clip does not align with the corresponding bore in the flush plate. The clips can also be easily bent or twisted during installation into their respective channels, thereby causing further alignment problems with the corresponding bores in the element being mounted. Also, such clips exhibit unsatisfactory resistance to lateral loads, since it is relatively easy for the clips to twist within their respective channels. Where wider elements are being mounted which require two clips in side-by-side relation, the installation is considerably more labor intensive, since installing two clips requires two separate installation steps. Also in a dual side-by-side clip arrangement, it is even more difficult to get the clips installed into their respective channels to the proper depth, since any errors in installing the two clips become cumulative in creating misalignment of the bores with respect to the flush plate being mounted.